Fiber couplers are essential parts of many fiber-optic systems. The term PM coupler has two separate meanings:

It could be a device that has one or more input fibers and one or more output fibers. The power distribution of light from an input fiber can occur at one or more outputs, depending on the wavelength and polarization. It could also be a device that couples light from the outside world into a fiber.

Here we’ll discuss the fiber couplers of the first type, which couple light from fibers to fibers. Couplers of this type can be made in a variety of ways:

  • Two or more fibers can be thermally tapered and fused so that their cores are nearby over a few centimeters. Polarization-maintaining fibers can also be utilized to make fused couplers, resulting in polarization-maintaining tap couplers or splitters.
  • Side-polished fibers are used in some couplers to allow access to the fiber core.
  • Pump–signal combiners and fiber-optic pump combiners are two types of multimode pump fiber combiners.
  • Rectangular lightwave circuits with branching waveguides and fibers linked to the inputs and outputs are available.
  • Bulk optics can also be used to make couplers, such as microlenses and beam splitters that can be coupled to fibers.

Fiber couplers are generally directional couplers. It implies that no optical power can be transmitted into one of the input ports and can be reflected into another. Return loss is frequently specified, and it reflects how much dimmer the back-reflected light is relative to the input, and it is usually rather large.

Fiber couplers are commonly used in the following applications:

  1. Cable TV system

A fiber-optic splitter receives the strong signal from one transmitter and transmits it over a number of output fibers for various consumers.

  1. Fiber Interferometers

Fiber couplers can be utilized in optical coherence tomography and other fiber interferometers (OCT). Such applications frequently necessitate the use of specially built broadband couplers.

  1. Fiber Ring Lasers

A dichroic fiber coupler can be used to inject pump light into the resonator of a fiber laser, and another fiber coupler can be used as the output coupler. This method is particularly beneficial in fiber ring lasers that lack resonator ends through which light could be pumped.

  1. Injecting Pump Light

Dichroic couplers are commonly employed in fiber amplifiers and lasers to inject pump light or remove residual pump light from the signal output.

  1. Combining the Radiation of Laser Diodes

Multimode fiber couplers are commonly employed in high-power fiber lasers and amplifiers to combine the radiation of several laser diodes and send it into the active fiber’s inner cladding (a double-clad fiber).

Contact a reputable PM coupler manufacturer if you require polarization-maintaining tap couplers or another type of PM coupler with unique characteristics.